Electron tube construction



Mam}! 1966 B. M. c. DRIARD ELECTRON TUBE CONSTRUCTION 2 Sheets-Sheet 1Filed Dec. 2, 1965 |.L\\\\ \II //VVE/VTO/? 5. A7. C. Drl'ard M WMATTORNEYS March 15, 1966 B. M. c. DRIARD ELECTRON TUBE CONSTRUCTION 2Sheets-Sheet 2 Filed Dec. 2, 1963 ATTORNEYS United States Patent ()fiice 3,240,976 ELECTRGN TUBE CONSTRUCTEQN Bertrand M. C. Driard, Paris,France, assignor to Compagnie Francaise Thomson-Houston, Paris, France,a corporation of France Filed Dec. 2, 1963, Ser. No. 327,186 Claimspriority, application France, Dec. 4, 1962, 917,455, Patent 1,352,175 7Claims. (Cl. 313-237) This invention relates to electron tubes havingimproved means connecting one or more of the electrodes therein with thelead-in or lead-out conductors of the tube. The term electrode as usedin the specification and claims is to be understood as designating anyone of the internal component elements of an electron tube requiring tobe connected with external circuit conductors for the operation or inthe course of the manufacture of the tube.

In conventional electron tubes, both of the vacuum and the gas-filledvarieties, the electrodes are usually permanently connected by spotwelding with conductor rods extending through and sealed in the envelopeof the tube, which rods at their outer ends constitute or connect withthe respective electrode terminals of the tube. With many of the moreelaborate types of tubes used in presentday electronics suchconstruction possessess distinct disadvantages. The internal structureof such tubes may be intricate and require a relatively great number ofWelded connections at closely-spaced points which are difficult ofaccess to a welding tool. Moreover such tubes are frequently large andexpensive and their process of manufacture is often complex and delicateand hence conducive to a relatively high percentage of defective tubeswhich are apt to be detected only in a final inspection step. In suchcases it would be desirable to able to dis mantel the defective tube andrecover valuable components of it, including the glass envelope, ratherthan scrapping the tube as a whole. The permanent electrode connectionsinside the tube make such recovery difiicult or impossible withoutdamage to the costly glass envelope. The afore-mentioned difficultiesare at least as serious when a plurality of electrodes or otherconstruction parts are joined in order to constitute a completesub-assembly. But it is precisely the condition in which the recovery ofthe parts of the tube is of a particular interest.

Objects of this invention include the provision of an improved method ofelectron tube construction whereby the assembly, and where desired thedisassembly, of the internal components of the tube will be considerablyfacilitated; the provision of an improved electrode tube assemblycontaining Within its sealed envelope one or more self-supportingsub-assemblies mounted in an improved manner achieving simplerconstruction and allowing the recovery of the electrodes and theirsub-assemblies as well as of the main part of the envelope. Otherobjects and advantages of the invention will appear.

According to a feature of the invention, means for connecting aninternal tube electrode with an external tube terminal comprises incombination a conductor rod extending through and sealed in the tubeenvelope and externally connected with said terminal, a resilientlyflexible conductor wire connected to said electrode internally of thetube, and means for connecting said Wire and rod comprising aresiliently expansible sleeve member on said 3,246,975 Patented Mar. 15,1966 wire engageable with a complementary end portion of said rod withinthe tube envelope. According to a further feature, an improved electrontube assembly comprises, within a sealed envelope at least onemechanically self-supporting sub-assembly comprising at least one tubeelectrode, means such as screw means for removably securing thesub-assembly to a support provided within the envelope, at least oneconductor rod extending through and sealed in the envelope, aresiliently flexible conductor wire extending from the, or each,electrode of said subassembly, and means including an expansible sleevefor detachably interconnecting said conductor wire with a relatedconductor rod.

Further features of the invention will appear from the ensuingdescription, relating to exemplary embodiments of the inventionillustrated in the accompanying drawings wherein:

FIG. 1 is a large-scale view, mainly in section, showing part of anenvelope of an electron tube and internal structure according to theinvention for connection with an electrode to be included in asub-assembly, which electrode and sub-assembly are not shown.

FIG. 2 is a similar view relating to modified structure; and

FIG. 3 is a simplified sectional view of an X-ray image intensifier tubeembodying features of the invention.

Referring to FIG. 1, reference 1 designates a portion of the glassenvelope of an electron tube. A conductor rod 2 extends through a nippleof the glass wall 1 and is sealed therein in a conventional manner. Theinner end of conductor rod 2, within the tube envelope 1, i.e., theupper end as shown in the drawing, is provided with a taper tip as at 3.A conductor wire 4 has its one, upper, end connected to an electrode,not shown, and has a slotted tubular sleeve member 5, made, e.g., ofspring bronze, or other metal composition having good electricalconductivity as well as resiliency, so as to be resiliently expansible,welded to the other end of wire 4. Preferably the wire 4 is welded tothe outer surface of the slotted sleeve 5 along the full length of ageneratrix of the sleeve, as shown, which generatrix is angularly spacedaround the circumference of the sleeve from the generatrices limitingthe slot of said sleeve. Sleeve 5 is so dimensioned and formed as to beengageable with a firm friction fit around the rod 2 and so that theradial resil iency of the slotted sleeve when thus fitted will ensureexcellent electric contact with the rod 2 over a relatively largesurface area. The end taper 3 of the rod facilitates engagement of thesleeve 5 thereover. The wire 4 is relatively stiff yet flexiblydeformable and is desirably formed with at least one coil loop 6therein, to increase its natural flexibility. Thus in the assembly ofthe tube a connector sleeve 5 can easily be brought into alignment withthe tapered end 3 of a conductor rod 2 and engaged thereover. Thisarrangement is especially convenient where the conductor wire 4 formspart of a sub-assembly including more than one electrode and associatedconnector wires such as 4, to be respectively connected with relatedconductor rods such as 2 extending through spaced points of the tubeenvelope. In such an assembly it will be realized that manufacturingtolerances may introduce variations in the relative spacing as betweenthe conductor rods and other components. Thus the deformability of theconnector wires 4 of the sub-assembly prevents any strain on theconductor rods while the tapers at the ends of these rods allow a smoothinsertion of all the conductor rods in all the sleeves.

In the modified construction shown in FIG. 2 parts corresponding toparts shown in FIG. 1 are designated with the same reference numerals.The difference over the first embodiment described lies in the fact thatthe conductor rod 2 has a conductive insert member 7 of enlargeddiameter fitted over its upper part by way of an axial recess in thelower end of the insert member. The insert member 7 is tapered at itsupper end and is adapted to receive the slotted. connecter sleeveprojecting from wire 4 tightly fitted thereover. This modification isuseful in cases where the conductor rod 2 is of small diameter in thatthe enlarged insert member 7 will facilitate connection with the sleeve.In the embodiment of the invention shown in FIG. 3 the invention isapplied to an X-ray image intensifier tube comprising a glass envelope 9of relatively large dimensions. This glass envelope comprises agenerally cylindrical portion 23 and a cover 2 5; the .two portions arebonded only after the assembly of the internal parts of the tube. At theupper end of the envelope 9 there is a primary image-receiving screen 20provided with fluorescent and photoemissive layers. At the lower end ofthe tube there is a smaller, secondary fluorescent screen 16 on which anintensified image is to be formed. An annular electrode 19 is providedaround a large diameter cylindrical intermediate portion of the tube,preferably in the form of a metal coating deposited on the tube wall,and is adapted to be connected through means not shown with a relativelylow potential for accelerating the photoelectrons emitted from thephotoemissive under side or photocathode of the primary screen 20. Thetube further includes a set of three annular electrodes 13, 12 and 14,coaxially aligned along the optical axis of the tube and constituting anelectron-optical lens system for concentrating the photoelectrons fromthe photocathode towards the secondary screen 16. The intermediateannular electrode 12 is provided with a plurality of evaporator elementssuch as which serve exclusively during the manufacture of the tube forvaporizing alkali metals and other substances initially introduced intothe tube and serving to form the photocathode layer on the under side ofprimary screen 20. The construction of an electrode 12 of this type isdescribed in greater detail in co-pendin-g application Serial No.327,185, filed December 2, 1963.

In accordance with the present invention, the electrodes 12, 13 and 14together with the evaporator elements 15 and other components formingpart of electrode 12 are previously assembled to provide aself-supporting unit or sub-assembly, ceramic posts such as 21 and 22being used for binding together the three electrodes which are carriedto different potentials. This sub-assembly is then secured by way ofscrews 17 to an annular supporting member 18 sealed to the inner surfaceof envelope 9 adjacent to a restricted lower end of it. Lead-inconductors are provided in the form of a number of conductor rodsextending through and sealed in nipples of the glass envelope 9 atsuitable positions. Only two such conductor rods are shown at 10 and 10,but it will be understood that as many such rods would be provided asthere are connections to be made from internal tube components toexternal tube terminals. In FIG. 3 rod 10 is shown connected to annularelectrode 12 and rod 10 to the heater elements 15. The con nection,generally designated 11, between each lead-in rod provided, such as 10,10, and the related electrode is similar to what was described withreference to FIG. 1 or 2, including a looped flexible wire extendingfrom the electrode and an expansible sleeve welded thereto forengagement over a tapered upper end portion of the related conductor rod10 or 10'. The connecting means are only illustrated in a general mannerin FIG. 3, since they were shown and described in detail earlier herein.

The advantages of the invention will be readily appreciated from theforegoing disclosure. After the above described sub-assembly has beeninserted in position in the envelope 9 and secured therein by means ofthe screws 17, the connection from each component electrode to theassociated lead-in rod such as 10, 10 can be very easily effected in themanner earlier described with reference to FIGS. 1 and '2 withoutrequiring the diflicult manipulation of a welding electrode under thecramped conditions present, and without requiring any great degree ofprecision in the relative positioning of the conductor rods 10, 1t) andother parts of the tube assembly or electrode :subassem=bly, owing tothe resilient deformability of .the connecting wires as earlierexplained. In addition, in the event of any defect in the tube assembly,during or after manufacture thereof, the electrode subassembly can beeasily removed from the defective tube, as by severing the cover 24 andby unscrewing the screws 17 and disengaging the slotted sleeve memberssuch as 5 (FIGS. 1 and 2) from the related lead-in rods such as 10, 10(FIG. 3), so that the expensive components can be reused partly orwholly in a different tube. Moreover the most costly parts of the glassenvelope of the tube remains undamaged.

It will be evident that various changes and modifications may beintroduced without exceeding the scope of the invention. Thus instead ofthe conductor rods being tapered as at 3 (FIG. 1) or 8 (FIG. 2), or inaddition to such taper, the slotted sleeve members 5 may be providedwith an enlarged, tapered entrance at their free or lower end. The X-rayimage intensifier device shown in FIG. 3 constitutes but one example ofthe many types of electron tubes to which the invention may be usefullyapplied.

I claim:

1. An electron tube having a sealed enclosure, a mechanicallyself-supporting inner sub-assembly comprising at least one tubeelectrode, supporting means within the enclosure, means detachablysecuring said sub-assembly to said supporting means, at least onelead-in conductor rod extending through and sealed in the wall of saidenclosure independent of said supporting means and connectable to aterminal externally thereof, and means connecting said at least oneelectrode with a related conductor rod inside the tube and comprising aresiliently flexible connecting wire extending from said said electrodeand a radially expansible slotted tubular sleeve of conductive materialsecured to one of a free end part of said wire and an inner end part ofsaid conductor rod and engageable with a tight fit over said other endpart.

2. The electron tube claimed in claim 1, wherein said connecting wirehas substantial stiffness and is looped to impart resilient flexibilitythereto.

3. An electron tube having a sealed enclosure, at least one mechanicallyself-supporting electrode assembly detachably secured to supportingmeans within the enclosure, at least one lead-in conductor rod extendingthrough and sealed in the wall of the enclosure independent of saidsupporting means and connectable to a terminal externally thereof, andmeans connecting said at least one electrode with an associatedconductor rod within the tube comprising a relatively stiff, resilientlyflexible connecting wire extending from the electrode, and aradially-expansible slotted tubular sleeve of conductive materialsecured to a free end part of said wire and engageable with a tight butremovable fit over inner end part of said conductor rod.

4. The electron tube claimed in claim 3, wherein said conductor rod istapered at its free end to facilitate engagement of said slotted sleevethereover.

5. The electron tube claimed in claim 3, wherein said sleeve is formedwith an entrance taper to facilitate engagement thereof over saidconductor rod.

6. The electron tube claimed in claim 3, wherein said 3,240,976 5 6conductor rod is provided with an enlarged upper por- 2,200,954 5/1940Giassberg 313271 X tion over which said sleeve is engageable.

7. The electron tube claimed in claim 3, wherein said JAMES KALLAM,Aclmg Primary Exammerconnecting wire is looped intermediate its one endand DAVID L GALVIN, Exam-Mn s 'd 1 i b a1 5 eeve mam er 5 A. JAMES,Assistant Examiner.

References Cited by the Examiner UNITED STATES PATENTS 648,516 5/1900Ochs 313-271 2,045,525 6/1936 Harries 313-146 X 10

3. AN ELECTRON TUBE HAVING A SEALED ENCLOSURE, AT LEAST ONE MECHANICALLYSELF-SUPPORTING ELECTRODE ASSEMBLY DETACHABLY SECURED TO SUPPORTINGMEANS WITHIN THE ENCLOSURE, AT LEAST ONE LEAD-IN CONDUCTOR ROD EXTENDINGTHROUGH SAID SEALED IN THE WALL OF THE ENCLOSURE INDEPENDENT OF SAIDSUPPORTING MEANS AND CONNECTABLE TO A TERMINAL EXTERNALLY THEREOF, ANDMEANS CONNECTING SAID AT LEAST ONE ELECTRODE WITH AN ASSOCIATEDCONDUCTOR ROD WITHIN THE TUBE COMPRISING A RELATIVELY STIFF, RESILIENTLYFLEXIBLE CONNECTING WIRE EXTENDING FROM THE ELECTRODE, AND ARADIALLY-EXPANSIBLE SLOTTED TUBULAR SLEEVE OF CONDUCTIVE MATERIALSECURED TO A FREE END PART OF SAID WIRE AND ENGAGEABLE WITH A TIGHT BUTREMOVABLE FIT OVER INNER END PART OF SAID CONDUCTOR ROD.